Scum drawoff



Dc. 2, 1941. c. I.1. KUPPER 2,264,912

- scUM DRAwoFF Filed oct. 21, 1939 @sheets-sheet 1 www Dec. 2, 1941. C, KUPPER 2,264,912

scUM DRAwoFF ZW/ff Ilia/010er Y Dec. 2, 1941. c. J. KUPPER 2,264,912

` scUM DRAwoFF Filed Oct. 2l, 1959 6 Sheets-Sheet 3 L ummm A :um Q Illllll" "-Y Y Y! f, f5.

gvwwwbofo mfwaw 2, 1941- C. J. KUPPER I SCUM DRAWOFF Filed oct. 21, 1959 6 Sheets-Sheet 4 Dec. 2, 1941. c. J. KUPPER SCUM DRAWOFF Filedv oct. 21,v 1939 6 Sheets-Sheet 5 www 6 Sheets-Sheet 6 /f/ /l /JZ Dec. 2, 1941. c. J. KUPPER i scUM DRAwoFF Filed oct. 21, 1959 I.. u Ll M Patented Dec. 2, 1941 UNI Tl: D STATES PATl-:N T OFFICE Charles J. Kupper, Bound Brook, N. J.

Application OctOber 2l, 1939, Serial N0. 300,626

(Cl. 21o-3) 8 Claims.

' either too high or tool low a percentage of moisture. The desired moisture content, of course, will vary with diierent methods of disposal, but

in most cases the volume of water `must be suf- Iicient to enable the scum to ilow through a pipe and be handled by a pump. An excess of water is undesirable and renders more diiiicult the subsequent treatment of the scum.

The primary object of this invention is to proportion of the mechanism disclosed in detail in Fig. 3,

Figure is a fragmentary, vertical, longitu tling tank,

vide methods and apparatus for removing the scum from surfaces of bodies of liquid, confined in settling tanks, or. the like, of various shapes in plan view, and concentrate the scum to a desired degree before passing the same onto subsequent disposal mechanisms, .such as digestors, incinerators, or the like.

A further important object of the invention is to provide methods and apparatus ofthe above mentioned type which may be operated either continuously or intermittently and, if intermittently operated, maybe controlled automatically in accordancewith elapsed time or the accumulation of scum.

Other objects and advantages of the invention will be apparent during the course .of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same: l

Figure 1 is a top plan view of one form of settling tank, or the like, with scum and sludge draw olf mechanism operatively associated therewith,

Figure 2 is a vertical sectional view taken `longitudinally through one of the settling tanks of Fig. 1, Y

Figure 3 is a detail, plan view of a fragmentary portion of the mechanism disclosed in Figs. 1 and 2 and illustrates more clearly the manner in which the removed scum is concentrated prior to being passed on to subsequent disposal apparatus,

Figure 4 is a verticahsectional view of the 55 Figure 6 is a plan view of a dierent form of settling tank with scum and sludge draw off mechanism operatively associated therewith,

Figure 7 is a central, vertical, sectional view taken through the mechanism of Fig. 6,

Figure 8 is a detail, vertical, sectional view taken on line 8-8 of Fig. 6, l

Figure 9 is a`detail, vertical, sectional view l takenon line 9-9 of Fig. 6,

Figure 10 is a detail, vertical, sectional view taken on line I 0-I 0 of Fig. 6,

Figure 11 is a detail, vertical, sectional view taken online I I-I I of Fig. 6, and

Figure 12 is a view similar to Fig. 6 but illustrates a modified form of concentrating or separating mechanism from that disclosed iny Figs. 6 to 9, inclusive.

Y In the drawings, wherein for the purpose of illustration are shown the preferred embodiments of this invention, and particularly referring to Figs. 1` to 4, inclusive, the reference character I 5 designates each one of two settling tanks which are arranged in parallelism, as best illustrated in Fig. 1. Each one of these tanks is of .rectangular shape in plan view, but it readily will be understood, as the description proceeds, that each tank could be of square formationin plan view, if desired.

Figs. 1 and 2 clear-1y illustrate the settling tank I as including a longitudinal bottom wall I6 which may be either sloping as shown or iiat, end walls Il and I8, outer side walls I9 and 20, and a common center wall 2I.- Adjacent the end w`a1l Il, the bottom wall` I6 of each settling tank is properly shaped to form a. pair of sludge collection hoppers or sumps 22, see Figs. 1 and 2.

Exteriorly of this end wall I'l, the two settling tanks I5 are provided with a common influent chamber 2,3. Extending inoppo-site directions from this inuent chamber are Athe separate influent channels 24, one being provided for each settling tank I5. Figs. 1 and 2 clearly illustrate each iniluent' channel 24 as having.a laterally sloping and longitudinally tapering bottom wall 25. These sloping and tapering bottom walls 25 are so arranged that the bottom portion of each channel 24 is widest and deepest at its end adjacent the iniiuent chamber 23.

outwardly or the mnuent chamber za and the dinally of the eilluent trough enlargement 28,'

there is formed a separation or concentrating chamber 29. A concentrated scumi receiving chamber is arranged next to the chamber 29. Raw sewage enters the influent chamber 23 by way of the influent pipe 3l. From the inuent chamber, the raw sewage flows over the V-notched Weir plate 32, see Figs. 1 and 2, into the influent channels. 24 for the two settling tanks I5. From each influent channel 24, the raw sewage, or industrial waste, is fed into its respective settling tank I5 through four pipes 33. These pipes are associated so as to discharge the influent against the inner surface of the end wall I1 of the setting tank.

The eiliuent is discharged from each settling tank I5 into the eiiiuent trough 21 through a discharge opening 34. The desired tank liquid level W, see Fig. 2, is obtained by means of a Weir plate 35. From the trough 21, the eiiluent is discharged through the pipe 36, see Fig. 1. For the purpose of moving the sludge, or settled solid, and the scum, or materials floating on or near the surface of the water, toward their respective points of collection and removal from the settling tanks, each tank is provided with an endless scraper conveyor. Each scraper conveyor includes the two chains 31 which are` trained over sprockets 3B, 39, 40, and 4I. The sprocket 38 is the drive sprocket for its respective chain, and this drive sprocket is mounted on a shaft 42 which is common to both drive sprockets for a given conveyor. Suitable transmission mechanism for driving this shaft 42 and its tyvo drive sprockets 38 is illustrated in Figs. 1 and 2 and is generally designated by the reference character 43. As many ditlerent types of drives may be employed, the one illustrated will not be described in detail. The sprockets 39 for the two chains of each conveyor are mounted on a shaft 44. This shaft is supported by suitable takeup bearings, not shown, which are used to maintain the conveyor chains at a desired degree of tautne'ss. Adjustment of the chains for this purpose is indicated by dash lines in Fig. 2. The

remaining sprockets 40 and 4I are mounted on shafts 45 and 45, respectively, which are supported in fixed bearings of any suitable construction.

The chains 31 of each conveyor are provided with a suitable number of wooden nights 41. The conveyors travel in the direction of the arrows in Fig. 2, and the flight chains for the horizontal runs of each conveyor are supported by the sprockets 38 to 4I and suitable tracks, not shown,

located below the liquid level and on the tank floor so that the upper iiights 41 move along the surface of the liquid to carry the scum toward the eilluent end of the settling tank and the lower nights 41 move the sludge along the tank oor I6 toward and into the sludge hoppers 22 at the inuent ends of the settling tanks.

The settled solids or sludge is withdrawn by a sludge pump, not shown, from the collection Lhoppers 22 through the pipes 48, 49, and 50 and is discharged into the inspection sludge sump 25. A valve 5I is provided in each pipe 49 for controlling the flow of sludge and liquid therethrough.

Positioned between the discharge or tail end of the upper run of each conveyor and the effluent discharge opening 34 is a. scum draw off pipe or trough 52. I'hese scum pipes or troughs 52 have an opening 53 for practically the whole width of their respective tanks. The troughs or pipes 52 are rotatably supported at their ends in bearings 54, 55, 56, and 51. The bearings 55 and 56 support the inner ends of the draw off pipes 52 in the common center wall 2I for the two settling tanks I5. This center wall 2I is provided with an opening 58 which registers with and establishes communication between the open, ad jacent ends of the two pipes or troughs 52. The bearing 51 is received in an opening 59 which is formed in the tank wall between the adjacent settling tank I5 and the scum separating or concentrating chamber 29. The end of 'the pipe or trough 52 which is received in this bearing 51 is open and is in communication with this chamber 29. Therefore, any scum that flows into the troughs or pipes 52, with an appropriate volume of liquid, will iiow through one or both of the pipes or troughs and will empty into the chamber 29.

Fig. 1 discloses each one of these pipes or troughs 52 as having an operating handle 6U. By means of these operating handles, the troughs can be rotated so that their entrance openings 53 will be adjustably arranged with respect to the water leve1 W of their respective tanks. Fig. 2 discloses the entrance opening 53 of one of the pipes or troughs 52 in a position above the liquid leve1. When in this position, no scum or liquid will flow into the pipe or trough 52. By suit ably rotating the pipe or trough in a counter-4 clockwise direction, as viewed in Fig. 2, the entrance opening 53 may be moved so that scum and an appropriate amount of liquid will flow through the opening into the pipe or trough.

Fig. 2 illustrates a handle or lever 60a of the trough 52 as being provided with power means for manipulating the same. In its closed Dosition, the lever 69a engages a stop SI and is maintained in this position by means of the spring 62. When it is desired to rotate the trough or pipe 52 so that its entrance slot 53 will receive scum from its settling tank, the solenoid 63 may be energized. This solenoid is supported for pivotal movement on the pivot pinll to take care of the arcuate travel of the free end of the lever 60a to which the solenoid armature is connected.

It is to be understood that this illustrated 'power mechanism is only one of many different types of devices which may be employed for manipulating the scum receiving trough pipe52 and that any other suitable mechanism may be employed to suit the occasion. Of course, the spring and solenoid may be reversed so that the spring will normally hold the associated pipe or trough in a scum receiving position and the soleoid be used to move the pipe into a closed posi- The scum reaches the separation or concentration box or chamber 29 with an undesirable percentage of liquid for most disposal plants. It is proposed, therefore, to reduce the percentage of liquid in this box or chamber. To accomplish this desired result, a pipe 65 extends from the Y amen lower portion of the box or chamber 29 into the endenlargement 28 of the effluent trough 21. The .upper end of this pipe 65 is provided with ai threaded weir sleeve or collars6 so that it mayO beA raised and lowered. To accomplish rotary movement of this sleeve or collar, a rack 61 is carried by the same. This rack is engaged by a toothed shaft 68. This toothed connection between the sleeve or collar 66 andthe shaft 68 may take different forms. For example, the shaft and rack may be of the worm type so that 29 then will drain into the chamber 90. The separated scum flows from the chamber 30 into the pipe 15 and may be carried by this pipe either directly to a dlgester, an incinerator, or the like, or the scum may be carried by this pipe to the inspection box 26 previously described as receiving the sludge from the collection hoppers or sumps 22 of the settlingv tanks I5. The sludge,

rotation ofthe shaft 68 will bring about rotation oi' the sleeve 66 or the shaft may take the form of a rack so that reciprocation of the same will bring about rotation fof the lsleeve or collar 66. Other suitablel mechanism may be employed for adjusting the sleeve or collar 66 to bring about raising or lowering Vof the `same due to its con- .nection with the pipe 65. If desired, the sleeve of the liquid in the box 29, a Weir plate extension or a gate 10 may be lowered into engagementwith the top edge of the weir plate 69. This WeirA plate extension or gate 16 may be raised and lowered by means of a cable 1I trained over an oscillating pulley sector 12 which is mounted on the shaft 19. This shaft may be actuated by any suitable f mechanism. Of course, any other suitable mechanism may be employed for controlling the ow of scum from the separating or concentrating box or chamber 29 into the outlet chamber` 30.

Of course, this scum removal and concentrating operation can be continuously carried on by arranging the scum withdrawing pipes or troughs 52 so that their openings 53 will continuously receive scum and liquid and by arranging the sleeve or collar 66 and by positioning the Weir plate 69 so vthat liquid will be continuously discharged from the box or chamber 29 and scum will be continuously passed over the Weir plate 69. Itis generally desirable, however, to intermittently Withdraw the scum from the settling tanks. Intermittent operation may either be manually controlledor automatically controlled. 1f it is automatically controlled, it may function in response to predetermined elapsed time intervals or in accordance with the accumulation of scum either at the draw off pipes or troughs 52 or in the sep.- arating or concentrating box or chamber 29. No attempt has been made to disclose automatic control mechanisms for the power operatingmeans of the'pipes or troughs 52, the sleeve or collar 66, and the Weir plate extension or gate 10, as any one of many different well known forms of control devices can be used.A

To obtain an accurate control of the percentage of liquid discharging from the separating or con' centrating chamber 29 with the scum, the level of the top edge of the sleeve or collar 66 is set a desired distance below the liquid level of the tank effluent weir plate 35, and thev top edge of the weir plate69 is set at an elevation slightly higher than the liquid level or the top edge of the adjustable sleeve or collar 66.

When it is desired to completely drain the concentrating or separating box 29the plug 14 may be withdrawn. The bottom portion of the box andthe sc um if it is carried to the inspection box v26, is discharged through thepipe 16 to the next succeeding apparatus of the disposal plant.

It is to be understood that I do not desireto limit myself to any particular form of collecting mechanism for the sludge and the scum. For that reason, I have illustrated a modification in Fig. 5. In this figure, a scraper conveyor 31a is illustrated, and this conveyor differs from the conveyor of Figs. l and 2 by having its upper run located below the water line W and not used to collect the scum. This conveyor,v therefore,.only

. functions to collect the sludge and move it toward its point of discharge from the tank. The scum in this modification is moved 'toward the discharge trough or pipe 52 by air jets 11. Otherwise, the scum collecting mechanism of Fig. 5 is the same as thatdisclosed in Figs. .1 to 4, in-

clusive; and similar reference characters will be applied to similar elements. n

In Figs. 6 to 11, inclusive,"there are disclosed round settling` tanks as distinguished from rectangular or square tanks. These round tanks 18 are formed with cylindrical side walls 19. A floor is provided for each tank and slopes toward its Adjacent the center of the tank floor 80,

center. a sludge collecting hopper or sump 8| is provided having a sludge draw off pipe 82 therefor. Thel influent for each tank is fed thereto through the influent pipe 83 and conduit 84 at the center of each settling tank. O

'I'he influent flows through the pipe 83 and into the conduit 84 and is discharged from the conduit through one or more suitable openings 85 into the cylindrical baille 86. Theinfiuent flows under this baille 86 and then over the upper edge of the cylindrical baille 86a into the settling tank.

This arrangement of baffles checks the fluid discharged through the openings 85 and affords an opportunity for considerable settling of material from the fluid immediately above the sludge collecting hopper or sump 8 I.

- An eluent trough 81 surrounds the upper part of each settling tank. The effluent flows into the effluent trough 81 by passing over-the top of the annular eiiiuent Weir 88. To prevent scum from following the eliluent over the Weir 88 into the ellluent trough 81, an annular bailie 89 is provided and is support-ed from the upper edge portion of the side wall 19 by mounting brackets 89a.

Rotatable sludge and scum collectors for each tank are clearly illustrated in Figs. 6 and '7. Journaled on the upper end portion of the conduit 84 is the inner end of a bridge structure `90.

The outer end `of this bridge is supported by collecting hopper or sump 8| by the scraper conveyor 98.

This sludge conveyor includes the pair of chains 91 trained over4 sprockets 98 and 99 which are xed to shafts and IOI, respectively. The shaft |00 is provided with a sprocket |02 over which is trained a drive chain |03 running over a drive sprocket |04 which is fixed to the shaft |05. Thedrive for this iatter shaft will be described at a later point. Conveyor ights |06 are suitably attached to the chains 91 and,

due to the direction of travel of the conveyor -as indicated by the arrow in Fig. '1, these iiights will move the sludge radially of the tank.

Figs. 6 and 7 disclose a scum plow |01 which is suitably attached to the carrying frame 94 of the bridge 90. The outer portion |08 of the scum plow is bent rearwardly and carries a part |09 which extends generally circumferentially of the tank, as is best illustrated in Fig.' 6. Hinged to the bridge 90 by means of the arms ||0 is a scraper III. This` scraper lies between the part |09 of the plow and the baille 89. Any suitable means, not shown, maybe employed for limiting the downward movement of the scraper. During rotary movement of the bridge 90, the scum iioating on the surface of the liquid in the tank is collected by the plow |01. To Aeffect outward movement of this scum relative to the main radially extending portion of the plow, a screw conveyor I I2 is mounted inV advance of the plow and is rotated in the proper direction to carry the scum to the bent portion |08 of the plow. The angle of .this bent portion |08 and the rotation of the bridge 90 cause the collected scum to be delivered to the scraper III.

The drive mechanism for the bridge and the various moving parts carried thereby now will be described. An electric motor II3 is mounted on the oor of the bridge 90. A chain, or other suit-` able drive, ||4 connects the motor to the radial line shaft |.I which is arranged beneath the bridge door. The outer end of this shaft IIS carries a sprocket wheel I I6 over which is trained an endless tow chain AI|1 that normally lies in the effluent trough 81. This chain is guided in its travel up to the sprocket wheel IIB by means of a sheave I8. By this means when the sprocket wheel is rotated the bridge 80 pulls itself about the tank, using the chain as a traction means. It will be recognized that thisv type of bridge propelling mechanism is conventional and the substitution therefore of other conventional propelling mechanisms, such as driving a hanged wheel 9| which runs on the track 92, is contemplated when desired.

The shaft |05 of the sludge collecting conveyor is driven from the line shaft I I5 by means of the bevel gears |I9 while the shaft of the screw conveyor II2 is driven from the line shaft ||5 by the chain and sprocket assembly |20. It will be appreciated that any desired differences in speeds between the various drive and driven shafts of the several mechanisms may be obtained by employing appropriate sized gear and sprocket wheels.

As the scum is collected in a settling tank, it is carried around the tank and the scum, with a certain amount of water, passes out of the settling tank over the submerged scum shelf plate I2|, see Figs. 6, 9, and l0. This self plate has a downwardly bent edge or flange |22 on its approach side to act as an inclined ramp for the material which is floating slightly below the sur- ,I face .of the water.' This scum shelf plate is a continuation of the bottom wall |23 of a scum trough |24 which bridges the eflluent trough in extending from the settling tank to scum separating or concentrating mechanism to be described. A guide |25 carries the tow chain II1 over the trough |24. To back up each scum shelf plate and to assist in guiding the scum thereon. a baille plate |28 is associated with the rear of the shelf plate and projects radially inwardly of the settling tank relative to said shelf plate. This baille plate |26 is clearly illustrated in Figs. 6, 9, and 10 as being hinged to the shelf plate |2| and as having a counterweight |21 for normally retaining it in its vertical position, sea Fig. 10.

As the scum plow |01, with its scraper III, see Figs. 6 and 10, approaches the scum shelf plate,

' the accumulated scum ows out of the settling tank over the shelf plate and the scum trough until thfe plow portion I 08 engages the pivoted barile plate |28. Further movement of the plow |08 causes the baiile plate to pivot about its hinge mounting and the plow passes beyond the plate. After the passage of the plow, the plate swings back to its normal position where it closes or obstructs the far side of the scum shelf plate I2I.

Figs. 6 and 9 clearly disclose that the scum troughs |24 bridge the efuent troughs 81 and deliver the scum into the separate concentrating or separating boxes or chambers |28, see Figs. 6, 7, 8, and 9. Figs. 6, 9, and 10 disclose a slide gate |29 at the discharge end of each scum trough which controls communication between the trough and its respective concentrating box or chamber |28. These gates |29 can be raised and lowered by any suitable mechanism, but Figs. 9 and l0 disclose the same as being actuated by a cable |30 attached to a sector shaped pulley |3| which is mounted on an operating shaft |32. Any suitable mechanism may be employed for actuating the shaft |32. Figs. 6. '1, and 9 clearly illustrate the two concentrating boxes or chambers |28 as being separated or divided by the intermediate partition |33. Figs. 6 and 8 disclose a channel 4|34 which extends between the eiiluent trough 81 of the two settling tanks 18. This channel |34 is provided with gates |35 at its opposite ends for controlling communication .between the channel and the respective eiiluent troughs 81. Anv additional gate |36 is provided intermediate the ends of the channel |34 and may be employed to divide the channel into two isolated sections.

Figs. 6 and 8 disclose a liquid draw olf pipe |31 extending from each section of the channel |34 downwardly into the respective concentrating boxes or chambers |28. Fig. 8 discloses one of these pipes |31,as having threadedly mounted on its upper end an adjustable weir sleeve or collar |38. By threading this sleeve in opposite directions, its upper edge may be raised and lowered. This adjustment may be accomplished by means of rack teeth |39 carried by the sleeve and a rotating or reciprocating, toothed shaft |40. The pipe |31, adjustable sleeve |38, rack teeth |39 and toothed shaft |40 are, for al1 practical purposes, the same as the elements 85 to 68 inclusive of Figs. 3 and 4. Reference may be made to these last mentioned figures for a clearer understanding of the designated elements of Fig. 8. By means of these pipes |31, liquid may be withdrawn from the concentrating or separating boxes or chambers |28 and fed to the respective etiiuent channels or troughs 81 of the two settling |38, the liquid withdrawn from the boxes or' chambers |28 may be delivered to either one or both of the eiliuent troughs 81.

At the remaining ends o f the concentrating boxes or chambers |28 there is provided a scum receiving tank or box |4|. This tank or box is clearly illustrated in Figs. 6 and 8. Each chamber or box |28 is provided with a sliding gate |42 which controls communication between the boxes or chambers |28 and the scum receiving tank or Fig. 8 discloses oneof these'tgates as being operated by a cable |43 which Ais trained over a sector shaped pulley, or the like, |44 carried by an operating shaft |45. This operating shaft may be actuated by any suitable mechanism.

Figs. 6.and 8 disclose a scum draw oi pipe |46 which may be employed for carrying the scum from the tank or box |4| to a digester, or some other means of disposal. Fig. 8 also discloses a pipe |41 with a valve |48 which may be employed for draining the concentrating or separating boxes or chambers |28. Figs. 6 and 11 disclose eiiiuent pipes |49 for carrying oil the `eiluent from the troughs 81. 'I'he pipes 82 and |48 may be interconnected, if desired, to mix the scum and sludge. Y

By means of the adjustable sleeves |38, carried by the upper ends of the pipes |31, and the gates |42, the percentage of liquid flowing from thev boxes or chambers |28 into the tank or box |4| with the scum may be very definitely controlled. The liquid level in the concentrating or separating boxes or chambers V|28 is controlled and maintained by the adjustable sleeves or collars |38 on the pipes |31. During operation of the mechanism, the top edge of the adjustable sleeve or collar |38 for each box or chamber |28 should be set at an elevation lower than the iiuid level in its respective settling tank 18. The top edge of each adjustable sleeve |38, also, should be 'slightly lower than the top of the eiliuent Weir 88.

It will be appreciated that by adjusting the various gates |28, |35, |36,- and |42 and the sleeves or collars |38 and leaving the same in their adjusted positions, the mechanism may be continuously operated. However, if it is desired matter.

troughs s1 of the two sealing tanks 1s. A. single scum-discharge gate |42', however, is deemed to be suiilcient. All oi the remaining elements of the mechanisml disclosed in Fig. 12 are the sameas those disclosed in Figs. 6 to 11, inclusive, and for that reason the same reference numerals willbeapplied thereto. l l

It is believed that persons skilled in the art will be able to readily determine the `mode of operationof each one of the scum draw oil.' mechanisms disclosed and described above without being provided with any additional explanatory It is believed to be important to note. however, thai'l each one of the scumirawoii' mechanisms disclosed and described embodies the principle of providing very accurate control of the amount of liquid which is discharged with the scum from the concentrating, separating, or

of operation where the scum is carried away from a settling tank, or the like, withY the large volume' of liquid which is discharged with the scum as a result of skimming the scum from the surface of the liquid in a settling tank.

It is tobe understood that theforms of thisl invention herewith shown and described are to be taken as preferred examples of the saine, and

Having thus described the invention, I claim: 1. The method of collecting and conditioningscum and sludge'from sewage and other liquid waste .comprisingI introducing raw sewage or waste into a settling tank favoring settling of sludge and accumulation of scum at the surface of the liquid, collectingv and removing the settled sludge, skimming the scum from the surface of the liquid and flowing it into a concentrating to intermittently operate the scum. draw off .the scum trough |23 or in the concentrating or separating boxes or chambers |28. Suitable automatic control mechanism may be employedl for these elements. No attempt has been made to disclose the same as many suitable devices are readily available on the open market.

chamber, with a percentage of liquid which is in excess of that desired for the finally conditioned scum, withdrawing the scum free eiiiuent from the settling tank, maintaining a constant liquid level' in the settling tank, removing the scum with the percentage of liquid desired for the finally conditioned scum from the top of the concentrating chamber, withdrawing the excess liquid from the bottom of the lconcentrating chamber and delivering it to the scum-free efuent, and maintaining a constant rate of withdrawal of the excess liquid by establishing the i necessary lrelationship between the capacity of the flow path for the excess liquid and the elevation of delivery of the excess liquid relative to Fig. 12 illustrates a modification in connection i with the concentrating or separating. chambers y or boxes disclosed in Figs. 6, 7, and 9. In Fig. l2,

a single concentrating or separating box or chamber |28' is employed instead of the two boxes or chambers of the preceding figures. With this arrangement, it is believed to be desirable to employ two liquid discharge pipes |31, although one pipe may be used. By employing two pipes, and by providing the gates |35 and |36, the liquid discharged from the box or chamber |28 may be discharged into either or both of the effluent the liquid level in the concentrating chamber.

2. The method of removing scum and sludge from sewage and other liquid waste and conditioning 'the removed scum and sludge for subsequent treatment in additional disposal mechanism comprising introducing raw-sewage or Waste into a settling tank favoring accumulation of the scum at the surface of the liquid, collecting the sludge from the bottom of the settling tank and conveying it to a 'point of withdrawal from the tank, skimming the scum from the surface of the liquid 'inthe tank and owing it into a concentrating chamber with a percentage of liquid which is in excess of that desired for the final-scum, withdrawing. sludge and'scum-free efliuent from the settling tank, maintaining a constant liquid level in the concentrating chamber, removing the scum with the percentage of liquid desired for the nal scum from the top of the concentrating chamber and mixing it with the withdrawn sludge, withdrawing the excess liquid from the bottom of the concentrating chamber and delivering it to the sludge and scum-free efiiuent, and maintaining a constant rate of withdrawal of the excess liquid by establishing the necessary relationship between the capacity of the iiow path for the excess liquid and the elevation of delivery of the excess liquid relative to the liquid level in the concentrating chamber.

3. Apparatus for collecting and conditioning scum from sewage and other liquid waste comprising a settling tank, an iniiuent for the tank, an eluent channel for the tank, means for skimming the scum from the surface o: the liquid in the tank and moving it toward the eiliuent channel, a scum concentrating chamber, means for receiving the scum collected from the settling tank and feeding it with an excess volume of liquid into the concentrating chamber, means for maintaining a constant liquid level in the concentrating chamber, a scum outlet for the upper portion of the concentrating chamber through which vthe scum and a controlled quantity of liquid are discharged, and means for drawing oi the excess liquid from the lower portion of the concentrating chamber and discharging itv into the eiliuent channel at a controlled elevation with respect to the liquid level in the concentrating chamber for maintaining a constant rate of discharge of the excess liquid.

4. Apparatus for collecting and conditioning scum from sewage and other liquid waste comprising a settling tank, an iniiuent for the tank, an eiiiuent channel for the tank, means for skimming the scum from the surface of the liquid in the tank and moving it toward the eiliuent channel, a scum concentrating chamber, means for receiving the scum collected from the settling tank and feeding it with an excess volume. of liquid into the concentrating chamber, means for maintaining a constant liquid level in the concentrating chamber, a scum outlet for the upper portion of the concentrating chamber through which the scum and a controlled quantity of liquid are discharged, a draw oil' pipe leading from the lower portion of the concentrating chamber to the eiiluent channel for discharging excess liquid from the chamber, and means operatively associated with the draw oil' pipe for varying the elevation at which it discharges the excess liquid relative to the liquid level in the concentrating chamber to maintain a constantrate of dischargerof said liquid,

draw off pipe for regulating the rate of discharge of the excess liquid.

6. Apparatus for collecting and conditioning sludge and scum from sewage or other liquid waste comprising a settlingtank, an iniiuent connected to the ta'nk, an eiiluent channel for the tank, means for collecting the sludge settled to thebottom of the tank and conveying it to a point of withdrawal from the tank, means for withdrawing the sludge from the tank, a scum concentrating chamber, means for skimming the scum from the surface of the liquid in the settling tank and feeding it with an excess volume of liquid into the concentrating chamber, means for maintaining a constant liquid level in the concentrating chamber including a scum outlet 5. Apparatus i'or collecting and conditioning scum from sewage and other liquid waste comprising a settling tank, an inuent for the tank, an eilluent channel for the tank, means for skimming the scum from the surface of the liquid in the tank and moving it toward the eilluent channel, a scum concentrating chamber, means for receiving the scum collected from the settling tank and feeding it with an excess volume of liquid into the concentrating chamber, means for maintaining a constant liquid level in the concentrating chamber, a scum outlet for .the upper portion of the concentrating chamber through which the scum and a controlled quantity of liquid arefdischarged, a draw off pipe leading from the lower portion ofthe concentrating chamber to the eiiluent channel for discharging excess liquid from the chamber, and

for the upper portion of the concentrating chamber through which the scum and a controlled quantity of liquid are discharged, a draw off pipe leading from the lower portion of the concentrating chamber to the eilluent channel for discharging excess liquid from the chamber.- and means operatively associated with the draw off pipe for varying the elevation at which it discharges the excess liquid relative to the liquid level in the concentrating-chamber to maintain a constant rate of discharge of said liquid; and means for bringing together the sludge withdrawn from the settling tank and the scum withdrawn from the concentrating chamber.

'1. Apparatus for collecting and conditioning scum and sludge from sewage or other liquid waste comprising a settling tank, an inliuent for the tank, an efliuent channel for the tank, said influent and efiluent channel being associated with spaced portions of the tank so that the sewage will flow directly from the former to the latter to provide the retention period lfor the sewage in the tank, means for collecting the sludge settling to the bottom of the tank and conveyingit through the tank in the direction opposite to the direction of iiow of the sewage to a point oi' withdrawal from the tank, a scum concentrating chamber, means for skimming the scum from the surface of the liquid in the settling tank and moving it in the direction of iiow of the sewage toward the emuent channel, adjustable means for receiving the' collected scum and feeding it with an excess volume of liquid at a desired rate into the concentrating chamber, a weir over which the sewage ows to the eiiiuent channel after it is freed of scum, a scum outlet for the upper portion of the concentrating chamber including an adjustable weir over which the scum and a controlled quantity of liquid are discharged, a draw off pipe leading from the lower portion of the concentrating chamber to the eiiluent channel for discharging excess liquid from the chamber, an adjustable Weir operatively associated with the efiluent end of the said pipe, and means for adjusting the discharge level of the pipe weir relative to the liquid level in the concentrating chamber to maintain a. constant rate ofdischarge of saidliquid.

8. Apparatus for collecting and conditioning scum from sewage or other liquid waste comprising a settling tank, an influent for the tank, an eiiluent channel for the tank, said influent and eiliuent channel being associated with spaced portions of the tank so that the sewage will flow directly from the former to the latter to provide the retention period for the sewage in the tank, a scum concentrating chamber, means for skimming the scum from the surface of the liquid in an adjustable sleeve carried by the end of the the settling tank and moving it in the direction i of flow of the sewage toward the eluent channel,

adjustable means for receiving the collected scum and feeding it with an excess volume ofliquid at adesired rate to the concentrating chamber, a.

Weir over which the sewage ows to the eluent channel after it is freed of scum, a scum outlet for the upper portion of the concentrating chamber including an adjustable weir over which the scum and a controlled quantity of liquid are discharged, a draw o pipe leading from the lower l0' CHARLES .I KUPPER. 

